Background: There is increasing evidence that presentation, progression, and management of atrial arrhythmias, such as atrial fibrillation (AF), differ between women and men. Bachmann’s bundle (BB) is the main route for interatrial conduction, and sex-related differences in structural and electrical remodeling of BB may contribute to differences in AF development between women and men. Objective: Investigate whether sex differences in the electrophysiological properties of BB assessed by high-resolution and density maps exist in patients with AF. Methods: Sinus rhythm at BB was recorded for 5 s during cardiac surgery. Potential voltage, low-voltage area (LVA), conduction heterogeneity, unipolar potential morphology, and conduction velocity were assessed for both men and women. Results: The study population consisted of 108 patients (73 men, 35 women). Women had significantly lower potential voltages (5th percentile: 0.7 mV [0.6–1.0] vs 1.1 mV [0.6–1.4], p = 0.028), more LVAs (10.8% [4.6–19.7] vs 4.3% [2.2–11.7], p = 0.012) and more long double potentials (11.1% [3.6–13.5] vs 5.0% [1.0–10.3], p = 0.015) compared to men. Conclusions: We observed sex-related differences in the electrical remodeling of BB in AF patients. Women have a higher proportion of low voltage potentials, and more abnormal potential morphologies compared to men. These findings may reflect sex-specific differences in the underlying substrate of AF at BB.

Background: Aging induces structural remodeling, altering atrial electrogram morphology. Over time, structural and consequently electrical remodeling creates a substrate for atrial fibrillation. In structural heart disease, age-induced remodeling comes on top of a pre-existing degree of structural remodeling due to pressure or volume overload. Objective: Investigate the severity of age-related electrical remodeling in patients undergoing surgery for structural heart disease by utilizing a high resolution epicardial mapping approach. Methods: Five seconds of sinus rhythm were recorded intraoperatively at the right atrium (RA), Bachmann's bundle (BB), the left atrium, and the pulmonary vein area. Potential voltage, low-voltage area (LVA) and conduction velocity (CV) were assessed in all regions. Results: 104 patients were included (62,5 % male, age: 26–84 years) and categorized in three age groups: young-age (age <60 years, n = 40), middle-age (age 60–71 years, n = 33), or old-age (age ≥72 years, n = 31) group. Compared to the young-age group, the old-age group had 1) lower median potential voltages at RA (4.65 [3.53–5.62]mV versus 5.94 [4.86–6.79]mV, p = 0.001) and 2) lower CV at RA (87.86 [82.53–96.67]cm/s versus 94.81 [90.14–98.59]cm/s, p = 0.016) and BB (83.38 [67.72–94.96]cm/s versus 98.84 [86.58–102.90]cm/s, p = 0.005). Conclusions: Age-related electrophysiological changes in patients with structural heart disease include reduction in atrial potential voltages and slowing of CV. These changes were less pronounced in the middle-age group. This indicates that electrical remodeling is a combination of both the underlying heart disease and the aging process. However, the less pronounced changes in the middle-age group may reflect a more gradual progression of age-related remodeling.